Autophagy Deficiency Compromises Alternative Pathways of Respiration following Energy Deprivation in Arabidopsis thaliana  . Issue 1 (14th July 2017)

• Record Type: Journal Article
• Authors: Barros, Jessica A.S.; Cavalcanti, João Henrique F.; Medeiros, David B.; Nunes-Nesi, Adriano; Avin-Wittenberg, Tamar; Fernie, Alisdair R.; Araújo, Wagner L.
• Is Part Of: Plant physiology. Volume 175:Issue 1(2017)
• Page Start: 62
• Page End: 76
• Publication Date: 2017-07-14
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.01576
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : During carbon starvation, autophagy is associated with protein degradation and impact energy status by regulating alternative respiration via the ETF/ETFQO through a yet unclear mechanism. Abstract: Under heterotrophic conditions, carbohydrate oxidation inside the mitochondrion is the primary energy source for cellular metabolism. However, during energy-limited conditions, alternative substrates are required to support respiration. Amino acid oxidation in plant cells plays a key role in this by generating electrons that can be transferred to the mitochondrial electron transport chain via the electron transfer flavoprotein/ubiquinone oxidoreductase system. Autophagy, a catabolic mechanism for macromolecule and protein recycling, allows the maintenance of amino acid pools and nutrient remobilization. Although the association between autophagy and alternative respiratory substrates has been suggested, the extent to which autophagy and primary metabolism interact to support plant respiration remains unclear. To investigate the metabolic importance of autophagy during development and under extended darkness, Arabidopsis ( Arabidopsis thaliana ) mutants with disruption of autophagy ( atg mutants) were used. Under normal growth conditions, atg mutants showed lower growth and seed production with no impact on photosynthesis. Following extended darkness, atg mutants were characterized by signatures of early senescence, including decreased chlorophyll content and maximum photochemical efficiency of photosystem II coupled with increases in dark respiration. Transcript levels of genes involved in alternative pathways of respiration and amino acid catabolism were up-regulated in atg mutants. The metabolite profiles of dark-treated leaves revealed an extensive metabolic reprogramming in which increases in amino acid levels were partially compromised in atg mutants. Although an enhanced respiration in atg mutants was observed during extended darkness, autophagy deficiency compromises protein degradation and the generation of amino acids used as alternative substrates to the respiration.